I'm not as familiar with many of the newer full IM parcours, but the former Gold Standard for very tough IM Bike course was IM Lanzarote. My wife raced it in the Pro Women's division a while back - she is a strong cyclist, and it definitely played to her strengths. She was able score a pay cheque and to secure a qualifying spot for the IM World Championships that year with a top-5 finish.

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Steve Fleck @stevefleck | Blog

Lanzarote is no slouch but TriRatings ranks IM Wales as the toughest bike course.

https://www.trirating.com/course-ratings/

Probably CDA or Canada

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the world's still turning? >>>>>>> the world's still turning

You're about like me as far as strengths/weaknesses. Guessing the goal is KQ? Unfortunately 4.1 isn't great compared to FOP AG cyclists. But what made me competitive was W/cdA (guessing same for you). So I targeted a flat race where you had to stay aero 99.9% of the time. IMFL is not a good choice because it's post Kona and you'll have a lot of the heaviest hitters going there to get the next years KQ out of the way. This makes the race very competitive at the front end and leads to less than a fair race as far as everyone having to break their own wind the whole time.

The race I chose was Maryland. Smaller field, just a few weeks before Kona so not a championship caliber field (like you'd normally see at FL or TX when it was NA champs with 75 slots). I basically rode the entire bike ride all alone. I passed quite a few quick swimmers in the first 20 miles then I think only 3-4 people passed me the entire ride. Rode 4:42 on 205/208 (2.75w/kg). It was easier for me to prep for this as it's super flat where I live and I could leave my house and ride 100 miles without hitting a stop light. You need to practice riding in aero for hours on end and not sitting up to stretch very often or at all. This kills most folks in a race like this that aren't prepared.

Thing with that is that's your best bet to play the cyclist or strong bike rider advantage........elevation. Flatter terrain means higher average speeds. At a higher average speed your relative advantage is lessened by the pretty much cubic nature of aero drag as speed increases.

Elevation is more like a 1:1 advantage in your capabilities much like running is. Not 1:1, but you get the idea.

I still say even if you're heavier but a stronger rider, as freaking hilly as possible. Everyone has to ride the same hills. Also true for technical nature if you're more gifted at that versus the eternal Zwift dweller triathlete.

Weak bike riders can hide behind a good CdA and flat/non-technical courses and lose less time due to strong riders pushing that wall of aero drag for a minimal gain.

This is why I'm not super happy with my weeknight worlds and local/regional bike racing scene. I could drop most of the guys I ride with like a rock if some climbs/hills are longer. But all the flattish/roller stuff where the big heavy strong dudes can dominate me don't tickle my fancy. And I'm not about to experiment with gaining 20lbs and taking up solely riding for Z6 efforts.

Ironman France. Not just the climbs but the descents coming back down into Nice allow the best cyclists to shine.

For comparison (based on my experience), IM Lake Tahoe, while it existed, had a lot of elevation but all the roads were wide and non-technical and it was really just about the engine and how much you wanted to push the speed on the downhills.

I think Wisconsin and lake placid are more challenging than MT in terms of elevation. Aside from the duplessis out and back, the rest of the course is very straightforward and decently fast if you ask me.

But I'd play more to your strength versus just profile. MT is pretty tame if you ask me outside of the duplessis section, and isn't really a threat to have super duper hot/challenging conditions. If you thrive hammering flats, choose a flatter course. The time deltas may not be as big but your relative strength advantage would still be there. If you thrive in the heat, choose CDA (lol). St George is probably an obvious candidate, and Tulsa is an interesting one too. Varied course, decent amount of elevation but very good potential for winds/adverse weather which can make the bike a struggle for weaker riders.

Definitely take advantage of your long-term altitude acclimatization. Racing at 5200-7700ft would be a huge advantage for you over most folks. I think you'd be remiss not to. For someone showing up from sea level on race week, we're talking about a 9-15% decrement in fitness, and that's if they manage their hydration well during that week and on race-day. If not, it can quickly become 12-20% fitness loss.

If racing at the elevation of IMMT, you'll not only be not advantaged, you'll be slightly disadvantaged by comparison to sea-level dwellers.

Fun anecdote: My wife raced a triathlon in Avon, Colorado (8,100ft, IIRC). We showed up 3 days before the event. At the time, I knew less about endurance sports and virtually nothing beyond long-since forgotten undergrad ex phys info on altitude. We made lots of bad choices. Her race performance was close to 20% off from predicted and it wasn't for lack of effort.

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Dr. Alex Harrison | Founder & CEO | Sport Physiology & Performance PhD
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I agree with Alex, you should pick a race that plays to your strengths. Your biggest strength is your altitude acclimatization, not your cycling. 4.1 w/kg at 1000ft is not really FOP ag'er. But 4.1 w/kg at 5500 feet, on the other hand...

I asked a similar question years ago before signing up for my first full. I was overthinking it and looking for the perfect race. Well, there is no perfect race for anyone. Anyone can show up to any race, and anyone can beat anyone on any given day.

My suggestion: do the race that excites you most and gets you out of bed excited to train everyday. And do the race where the logistics and schedule are the easy for you and anyone else attending.

If there was one race I would recommend it would be IMMT. Forget what course is like but the venue is amazing. The hype, energy, and experience is unlike any other race I've ever done (and I've only done the 70.3) outside of Kona.

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blog

I agree with Steve. And choose the race that lines up with your lifestyle and training ability.
E.g. a teacher has the whole summer to train so race before you go back to school. Compared to a accountant another professional with a different busy season.

Also do not pick races that display strengthen. Pick races that hide your faults.

Bad swimmer avoid no wetsuit.
Bad in the heat avoid heat.
Thin skinned avoid cold .
Etc.

Side note. On the hardest bike years in kona the best bikers had the best bike splits and slowest runs. Vs easy days were you biker had the fastest bike split and fast run split.

If you choose to bike hard to get a head you will not do well, hills or no hills , wind or no wind.

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Technique will always last longer then energy production. Improve biomechanics, improve performance.
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It very much depend what you are looking for...

If you are looking big steady power (using the same 3 gears)... pick a flat course.

North American hilly courses are generally not very technical (very little braking on the downs).

European hilly course (ie: Nice) are 'technical', a little more fun / terrifying... but the strong locals are really good at that stuff
(ie: at Nice World 2019, there was no north American in the top 50 of my AG)

Depend if you want to use your cycling strength to enjoy the day or to win something.

+1000

Damn, a lot to think about here.

Mostly that I need to get my bike much stronger. hah. I do well in 70.3's, but KQ'ing is obviously a different game.

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@floathammerholdon | @partners_in_tri

As other have said, I would go about it in a bit of a different direction.
If my math is right you are about a 310 FTP, and while you are light, you are not South American 130 LB light. So use you FTP to get off the bike in as short of a time as possible and have more for the run.
IMAZ. If you ride at 73% FTP (226 Watts) you are looking at a 5-515 bike (depending on aeroness and pacing) Also IMAZ rides like a 95 mile course, because almost all of the last 18 miles is downhill (on the "normal course" not sure if they are changing it) so if you mess up your pacing, or nutrition, you have kind of a buffer to ride easy back into t2 and fuel on the way.
Less time on bike= faster run, especially if you don't find running a strength.

This is the most slowtwitchy nonsense. My FTP is also precisely 4.1 and a quick look shows my bike splits have ranged from 1st to 12th (second worst after the 12th is a 7th) in my age group (either m35-39 or 40-44) in all races since 2017.

To the OP, assuming you want a North American event …

IMSG for hardest bike, includes altitude, requires swimming in the cold and coping with heat
IMCHOO or COZ if you can deal with heat but suck at swimming
IMLP if you suck at swimming and cannot deal with the heat
IMWI if you are good at swimming and also handling your bicycle

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Dimond Bikes Superfan

I agree. Have done Whistler, Tremblant and Wisconsin and Wisconsin is by far the toughest.

Lots of punchy climbs and several long steep climbs. Very technical and not many flat, straight stretches to get in a rhythm.

4.1w/kg and 310w is fantastic, assuming you can back it up on an IM split with a ~75% FTP ride (~233w). That should be easy enough even if you take 5 hours (that’s 281 TSS, a pretty reasonable ride if you’re well trained and “racing”, rather than just going for a finish). Unless you’re as aero as a barn, you should easily go under 5 hours on a flatter course with that power. That said, I definitely agree on going for a hard bike. The slower bike splits you see, the better.

I recognize most on ST have thought of this, but if not, I’ll share because I find it really fun to look at the numbers. So, here’s some fun math as to why slow average speed bike split races are a strong rider’s best friend:

20mph = 5:36:00 ~172w
21mph = 5:20:00 ~194w
Time savings for 1mph = 16 minutes
Power difference = 12w

23mph = 4:52:10 ~245w
24mph = 4:40:00 ~273w
Time savings for 1mph = 12:10
Power difference = 28w

To get that same 16:00 if your competitor is theoretically riding 23mph, you need to go 24.24mph, ~280w, a massive 35w (something like 15%) difference.

So, double the difference in power on a fast course is only worth 2/3rds the time advantage. Couple that with the extra load of pacing well on a hilly bike, and you can really make your strengths work for you as a strong rider. The opposite, of course, is true for great runners. You want the fastest possible split for everyone else on the bike because the run is where the time gains for you would happen.

Assumptions for power: identical settings for weight, rolling resistance, aerodynamics (this is a big one, though obviously quite variable), 112 miles exactly, and 0ft elevation gain. I’m using the BikeCalculator app set to riding in the drops for aerodynamics rather than aerobars, as only a very optimized position is close to realistic on the app in my experience. It’s fantastic for back-of-napkin math, but it’s certainly no BestBikeSplit.

I would suggest picking a race based on location and time of year. Unless you like riding inside or in the cold, I'd look for something in the summer/early fall.

Anyone mentioned IM Texas in Woodlands? IM Waco should be okay too, but run course will kill you. Starky got bike course record in IM Texas and there's a reason. Course is Hardy toll road and it's flat and easy. You can drive from Colorado too. I drove from TX to Denver at one shot with no problem before. Anyway, think about it.

Wouldn't the 1000-strong draft pack negate his advantage as a strong cyclist?

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Excellent advice!

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Kiwami Racing Team

It happened that year and hopefully IM will make things better in the future.

Hardy Toll Road is definitely nice and once draft rules are enforced well, strong cyclists can really enjoy the course.

I don't think a tough bike course is going to help. In an IM you need to keep 70% or even 65% of your FTP, consistently, if you want to run well. If your idea was to attack the hills to get away you will be walking the marathon.

You can attack in a HIM and still be able to run 13 miles. (I know because when I was younger and inexperienced that's how I've done it and the run was still fine.) But in an IM you will gain 10-15 minutes on the bike to lose 2 hours in the run.